It's a curious line, and while when I read it I let it pass with conditional assent, I now think it's incorrect.

Wall Street has poorer-than-usual ethics, and does commit crimes for profit, but in general it is wary of the legal system. Wall Street tends not to exploit opportunities that run afoul of the legal system, even when they are risk-adjusted comparable to other opportunities. They would rather make money legally than illegally, if they can help it.

To use the wording of the article, Goldman Sachs (Wall Street) typically does not commit crimes when "the potential revenue from the crime [is] greater than the probability adjusted weight of getting caught", even if you set the adjusted revenue to average profitability.

In particular, Goldman Sachs (Wall Street) is gunshy with respect to the US legal system. From a charitable standpoint, perhaps this is out of an ethical respect for the law. From a cynical standpoint, perhaps there is another more involved risk calculation which takes into account long-term reputation and the unpredictability of political administrations and legal settlements. Given a long enough outlook cynical self-interest approaches ethics.

The point of grandparent was precisely that you let it pass on a first reading. It doesn't matter whether it's true, it's a huge image shift.